System and a method for detecting loudspeaker chain failure

Abstract

A method and a system for monitoring operation of at least one loudspeaker in a system comprising a plurality of loudspeakers connected in series on a same amplifier output in at least one loudspeaker chain driven by an amplifier board, the method comprising measuring a current consumed by the amplifier in an operating position of the plurality of loudspeakers, yielding a reference current; stopping the masking system into an idle position; emitting the reference signal, measuring an idle current consumed by the amplifier; and comparing the idle current with the reference current. The system comprises a microprocessor unit and a current measurement module, wherein the current measurement module is configured to measure a current drawn by the amplifiers and feed a resulting signal to the microprocessor unit; and the microprocessor unit generates an output signal to respective output channel.

The invention claimed is: 
     
       1. A controller/amplifier board for a system comprising loudspeaker chains, comprising:
 a current measurement module on a DC amplifier supply line of the system; and 
 a microprocessor unit; 
 wherein, for monitoring the loudspeaker chains, said current measurement module is configured to measure an idle current I idle  drawn by an amplifier power supply in absence of emission of signal, and a stimulated current I m , drawn by the amplifier power supply during emission of a stimulation signal by the microprocessor unit at a respective output channel via a respective amplifier to each loudspeaker chain of the system; and said microprocessor unit determines an impedance of each loudspeaker chain from the idle current I idle  and the stimulated current I m , compares the determined impedance with a nominal impedance of the loudspeaker chains, and, above a threshold difference between the nominal impedance and the determined impedance, emits a signal of failure of the loudspeaker chain. 
 
     
     
       2. The controller/amplifier board of  claim 1 , wherein said current measurement module comprises a current sensor inserted on the DC amplifier supply line; the microprocessor unit receiving a signal from the current sense amplifier. 
     
     
       3. The controller/amplifier board of  claim 1 , wherein said current measurement module comprises a current sense amplifier and said current sense amplifier amplifies a voltage drop across the current sensor with a fixed gain. 
     
     
       4. A method for monitoring a loudspeaker chains system, comprising:
 Measuring by a current measurement unit an idle current I idle  drawn by an amplifier power supply of the system in absence of emission of signal; 
 measuring b the current measurement unit a stimulation current I m  during emission of a stimulation signal V output  to each loudspeaker chain of the system; 
 determining by a microprocessor unit an impedance of each loudspeaker chain; 
 comparing by the microprocessor unit of the determined impedance of each loudspeaker chain with a nominal impedance each loudspeaker chain; and 
 if the difference between the determined impedance and the nominal impedance is above a threshold emitting a signal of failure of the loudspeaker chain. 
 
     
     
       5. The method of  claim 4 , comprising determining the impedance of the loudspeaker chains from a supply voltage of the system (V supply ), the stimulation signal V output , the stimulation current I m , measured at each loudspeaker chain, the reference idle current I idle  and an efficiency of the loudspeaker chains of the system. 
     
     
       6. The method of  claim 4 , wherein the stimulation signal is a low frequency signal selected to optimize the stimulation current I m . 
     
     
       7. The method of  claim 4 , comprising using the following relation:
 Impedance=V output  / I output    
 with I output =(V supply /V output )*(I m  −I idle ) * Amp eff ; where V supply  is DC supply voltage of the amplifier; and Amp eff  is efficiency of amplifiers of the loudspeaker chains. 
 
     
     
       8. The method of  claim 4 , wherein the nominal impedance of each loudspeaker chain is specified by manufacturers. 
     
     
       9. The method of  claim 4 , comprising, after said measuring the stimulation current I m , on each loudspeaker chain; setting the system in an operating position and measuring operation current of each loudspeaker chain and comparing the operation current to the idle current I idle ; and, above a threshold difference, emitting a signal of failure of the loudspeaker chain. 
     
     
       10. The method of  claim 4 , wherein the stimulation signal V output  is a low frequency sinusoidal signal stimulating each chain successively. 
     
     
       11. The method of  claim 4 , wherein the stimulation signal V output  is selected as a low frequency sinusoidal signal. 
     
     
       12. The method of  claim 4 , wherein said generating the stimulation signal V output  is selected as a low frequency sinusoidal signal maximizing the stimulation current. 
     
     
       13. A method for monitoring a problem with a least one loudspeaker in a system comprising a chain of loudspeakers connected in parallel on a same amplifier output, comprising:
 measuring by a current measurement unit a current consumed by the amplifier in absence of output signal emitted, yielding an idle current consumption of the amplifier; 
 measuring b the current measurement unit a current consumed by the amplifier when emitting a low frequency signal to the loudspeakers chain, yielding a stimulation current consumption of the amplifier; 
 determining by a microprocessor unit an impedance of the loudspeaker chain from the idle current consumption and the stimulation current consumption and comparing by the microprocessor unit the impedance with a nominal impedance of the loudspeaker chain and if the difference is above a threshold signaling failure of the loudspeaker. 
 
     
     
       14. The method of  claim 13 , comprising measuring the current consumed by the amplifier in the absence of output signal emitted, selecting a stimulation low frequency; stimulating the chains of loudspeakers at the selected stimulation low-frequency; measuring a resulting stimulation current consumption of the amplifier; and comparing the stimulation current consumption with the current consumed by the amplifier in the absence of output signal emitted. 
     
     
       15. The method of  claim 13 , comprising measuring the current consumed by the amplifier in the absence of output signal emitted, selecting a stimulation low frequency; stimulating the chains of loudspeakers at the selected stimulation low-frequency; measuring a resulting stimulation current consumption of the amplifier; and comparing the stimulation current consumption with the current consumed by the amplifier in the absence of output signal emitted, wherein said selecting the stimulation low frequency comprises selecting a low frequency maximizing the measured stimulation current. 
     
     
       16. The method of  claim 13 , comprising measuring the current consumed by the amplifier in the absence of output signal emitted, selecting a stimulation low frequency; stimulating the chains of loudspeakers at the selected stimulation low-frequency; measuring a resulting stimulation current consumption of the amplifier; and comparing the stimulation current consumption with the current consumed by the amplifier in the absence of output signal emitted, wherein said selecting the low frequency comprises selecting a frequency at a frequency range between about 20 Hz and about 100 Hz. 
     
     
       17. The method of  claim 13 , comprising measuring the current consumed by the amplifier in the absence of output signal emitted, selecting a stimulation low frequency; stimulating the chains of loudspeakers at the selected stimulation low-frequency; measuring a resulting stimulation current consumption of the amplifier; and comparing the stimulation current consumption with the current consumed by the amplifier in the absence of output signal emitted, wherein said selecting the low frequency comprises selecting a frequency at a frequency range between about 20 Hz and about 60 Hz. 
     
     
       18. The method of  claim 13 , comprising measuring the current consumed by the amplifier in the absence of output signal emitted, selecting a stimulation low frequency; stimulating the chains of loudspeakers at the selected stimulation low-frequency; measuring a resulting stimulation current consumption of the amplifier; and comparing the stimulation current consumption with the current consumed by the amplifier in the absence of output signal emitted, wherein said selecting the low frequency comprises selecting a frequency at a frequency range between about 40 Hz and about 60 Hz. 
     
     
       19. The method of  claim 13 , comprising measuring the current consumed by the amplifier in the absence of output signal emitted, selecting a stimulation low frequency; stimulating the chains of loudspeakers at the selected stimulation low-frequency; measuring a resulting stimulation current consumption of the amplifier; and comparing the stimulation current consumption with the current consumed by the amplifier in the absence of output signal emitted, wherein said selecting a stimulation signal comprises selecting a frequency maximizing high current and a low acoustical emission and an amplitude maximizing current.